The present invention relates generally to valving arrangements and more particularly to guides for one valve member in such a valving arrangement. Even more particularly, the present invention relates to valve member guides in the environment of pressure relief valves.
Pressure relief valves are old and well-known and may, for example, be employed in steam boiler or compressed air arrangements as a safety device and have found a widespread use in the petrochemical industry. Such valves are typically spring loaded to a closed position and, when the pressure in a specified region of the valve exceeds some preselected value, the valve opens venting that excess pressure to the atmosphere or elsewhere to prevent harmful explosions or system damage.
One such safety or relief valve currently manufactured by the applicants assignee has a valve seat fixed within a valve housing and a moveable stem supported valve member which is spring biased toward that valve seat with the valve stem sliding in a guide member as the valve opens and closes. This valve stem guide is a comparatively expensive component of the valve requiring an accurate sliding fit with the valve stem. The accumulation of dirt, corrosion or other accumulation of material on the valve stem, sometimes prevents or impedes the opening of the valve when in fact the valve should open to relieve pressure within the system.
It would be highly desirable to eliminate this sliding motion between a valve stem and a valve guide while retaining the ability to reseat the valve member accurately on the valve seat without use of a sliding guide mechanism.
In copending application Ser. No. 424,891, filed Sept. 28, 1982 now abandoned, there is disclosed a flexible guide for a valve member which in the preferred form has a central portion thereof captive between a pair of coaxial valve stem portions and having a series of spiral spokes coupling that central portion to a peripheral portion which is anchored to the valve housing. The arrangement of this copending application desirably eliminates sliding motion between the valve stem and stem guide with the valve stem executing a somewhat helical motion when actuated. This arrangement generally works well providing the desired results, however, in some installations, stress points have become excessively high. In some cases it would also be desirable for the length of the member interconnecting the inner and outer disc portions to be longer than that readily obtainable in a spiraling spoke design.